In a nitride semiconductor ultraviolet light-emitting element such as an LED (Light Emitting Diode) or an LD (Laser Diode) in which AlGaN-based semiconductor layers are formed on the main surface of a sapphire substrate, a lens may be provided for the purpose of increasing light extraction efficiency and the like.
For example, Non-Patent Document 1 proposes a nitride semiconductor ultraviolet light-emitting element in which a hemispherical lens is bonded to the rear surface on the side opposite to the main surface (the surface where an element structure part that emits light upon energization is formed) of a sapphire substrate.
Further, for example, Patent Document 1 proposes a light-emitting element in which the rear surface and the side surface of a sapphire substrate are sealed with a glass material whose surface shape is a spherical surface. Note that, the glass material employed in the light-emitting element proposed by Patent Document 1 is mainly composed of TeO2, which withstands ultraviolet light and blue-color light, but is greater in refractive index than sapphire.